1. Field of the Invention
The present invention relates to a process for preparing cationic resins, to aqueous dispersions of the cationic resins, and to the use of these dispersions in cationic electrodeposition.
2. Brief Description of the Prior Art
Cationic electrodeposition resins are well known in the art. For example, U.S. Pat. No. 4,104,147 to Jerabek et al discloses cationic electrodepositable resins which are formed from reacting a polyepoxide with a primary or secondary amine and solubilizing the polyepoxide-amine adduct in aqueous medium with the aid of acid. The polyepoxide is contacted and heated with a polymeric polyol, for example, a polyester polyol such as a polycaprolactone diol or a polyether polyol such as polyoxytetramethylene glycol before reaction with the primary or secondary amine.
U.S. Pat. No. 3,839,252 discloses quaternary ammonium salt group-containing resins which are formed from reacting a polyepoxide with a tertiary amine salt. The polyepoxides are optionally contacted and heated with a polyether polyol such as polyoxypropylene glycol or polyoxyethylene glycol before reaction with the tertiary amine salt.
U.S. Pat. No. 4,260,720 discloses cationic electrodepositable resins which are derived from a polymercapto-chain extended polyepoxide. Among the polyepoxides which may be used are polyglycidyl ethers of cyclic polyols such as bisphenol A and 1,2-bis(hydroxymethyl)cyclohexane. These polyepoxides can be produced by etherification of the cyclic polyol with epichlorohydrin in the presence of alkali. Besides bisphenol A and 1,2-bis(hydroxymethyl)cyclohexane, oxyalkylated adducts of these cyclic polyols such as ethylene oxide and propylene oxide adducts can be used.